FIELD OF THE INVENTION
The present invention relates to a railroad gate arm which is used at railroad crossings and operated so as to be lowered to a horizontal position to block traffic when a train is present and to be raised to an upright or retracted position when no train is present.
More particularly, the invention relates to a swivel type gate arm which is designed to pivot about a longitudinal axis when an external force is applied to the gate arm. Such known swivel mechanism is in addition to the well known breakaway mechanism which is normally incorporated in gate arm support members so that if a car or truck engages the gate arm head on, the arm will break away without destroying the relatively expensive support mechanism which supports the gate arm and raises and lowers the same.
A swivel type gate arm is disclosed in U.S. Pat. No. 5,442,878. In FIG. 2 of the foregoing patent, there is shown a gate arm 22 which is fixedly secured to a swivel bracket 46, the swivel bracket 46 being supported on a pin-like member 44 shown extending from a conversion bracket 42. The gate arm 22 pivots up and down about an axis (not numbered) which is located at the center of a motor 41. In addition, the bracket 46 can rotate or swivel about the gate adapter 44 with the result that when an external force is applied, the gate arm 22 can swivel about the axis of gate adapter 44. The purpose of allowing the gate arm to swivel about the axis of gate adapter 44 upon application of an external force is to reduce breakage of the gate arm, whether such external force is caused by high wind or due to contact with the top of a vehicle.
The swivel gate arm disclosed in the foregoing '878 patent is intended to be maintained in a preferred position in an upright plane due to gravity. However, such mechanism has been found to be unsatisfactory. Thus, it is an object of the present invention to provide a swivel adapter spring assembly which will reliably return a gate arm to an upright plane in the absence of external forces which are strong enough to overcome the spring force.
It is a further object of the invention to provide a spring assembly which is highly advantageous and uniquely qualified to control the position of a swivel type gate arm without need to rely upon gravity.
The foregoing objects and advantages of the invention will be apparent from the following description of a preferred embodiment thereof, taken in conjunction with the accompanying drawings.